Lubricating compositions containing metal derivatives of 1, 3-bis (hydroxy-aralkyl)-2-imidazolidinethiones



United States Patent James M. Calfrey, .lr., Beacon, and Herman l). Kluge and John E. Tessieri, Wappingers Falls, N. Y., assignors to The Texas Company, New York, N. Y., a corporation of Delaware No Drawing. Application June 5', 1952, Serial No. 291,994

6 Claims. (Cl. 25242.7}

The present invention relates to improved lubricating compositions, and more particularly to lubricating compositions containing metal derivatives of substituted cyclic thioureas.

It is common practice to add to mineral lubricating oils small amounts of so-called detergent compounds of various types, which have the property either of reducing the formation of gums and sludges, normally occurring; as a result of the oxidative or other deterioration of the'oil under service conditions, or of dispersing and altering the character of any gums and sludges formed so as to reduce the formation of varnish-like deposits upon the lubricated engine parts.

Among the compounds which have been proposed as lubricating oil additives of the detergent type are the metal derivatives of condensation products obtained by interreacting hydroxyaromatic compounds with aldehydes and with amines, including polyamines containing at least two reactive, i. e., primary or secondary, amine groups, as disclosed in U. S. 2,353,491. The hydroxy metal'and alkoxy metal derivatives of such condensation products, disclosed in the copending application of H. D. Kluge and F. W. Moore, Serial Number 287,266, now Patent No. 2,725,357, filed May 10, 1952, have been found to be particularly eifective for this purpose. However, the above compounds have also been foundto exert a pronounced pro-oxidant efiect upon lubricating oils at elevated temperatures, Which results in an objectionable increase in the acidity of the oils during use. Sulfurization of these compounds by reacting them with sulfuror a sulfur halide, as disclosed in U. S. 2,459,114, accomplishes some improvement in their pro-oxidant activity, but also largely destroys their detergent properties.

This invention is based upon the discovery that very superior detergent-type additives for mineral lubricating oils are obtained by reacting certain compounds of the above type \ilith carbon disulfide. We have found that the sulfur-containing compounds thus obtained have excellent detergency characteristics equivalent to the corresponding unsulfurized compounds, but without the objectionable pro-oxidant characteristics of the latter.

The novel lubricating oil additives of this invention are .metal derivatives of reaction products obtained by first interreacting a hydroxyaromatic compound with an aldehyde and with a polyamine containing two primary amine groups separated by two carbon atoms, so as to form a condensation product, and then further reacting this condensation product with carbon disulfide. The metal derivatives include the normal metal salts and the hydroxy-metal and alkoxy-metal derivatives. Preferably, the compound contains at least one aliphatic hydrocarbon group of suificient chain length to impart oil-solubility.

Typical hydroxyaromatic compounds which may be employed in forming the condensation product include phenol, diamyl phenol, pentacosyl phenol, alphaand beta-naphthol, octadecyl 'alphaand beta-naphthol,

cat ech ol, benzylphenol, chlorphenol, hydroquinone, phea mild oxidizing agent such'as iodine.

1101 resins, and the like. The preferred compounds of this class are alkyl hydroxyaromatic compounds containing at least one aliphatic hydrocarbon substituent group of from about 5 to 30 carbon atoms. The terms alkyl hydroxyaromatic, alkyl pheno etc., are used for convenience in the specification and claims to mean compounds containing one or more aliphatic hydrocarbon groups, which may be either saturated or unsaturated in character.

Aldehydes employed in forming the condensation product are preferably aliphatic aldehydes such as formaldehyde, acetaldehyde, butyraldehyde, furfuraldehyde, etc., although aromatic aldehydes such as benzaldehyde, toluic aldehyde, etc., may also be employed if desired. The aldehydes may contain substituent groups such as hydrocarbon groups, alkoxy groups, nitro groups, halogens, etc., insofar as these do not interfere in the condensation reaction.

The polyamine employed in forming the condensation product is preferably ethylene diamine, or a hydrocarbon compound which may be regarded as a derivative of ethylene diamine, preferably such derivatives wherein not more than one hydrogen on each methylene group is substituted by a hydrocarbon group. As examples of such compounds may be mentioned 1,2-propylene diamine, 1,2-butylene diamine, 2,3-butylene diamine and phenyl ethylenediamine. Aromatic compounds contain ing adjacent primary amine groups, such as orthophenylene diamine, 'may also be employed. The amine may contain various substituent groups as discussed above in connection with the aldehyde reactant.

The condensation reaction is suitably carried out by heatingthe reactants together at a moderately elevated temperature, such as a temperature in the range of about IOU-200 F., in the presence or absence of a solvent. The reactants are preferably employed in approximately equivalent reacting proportions, i. e., about equimolar proportions of hydroxyaromatic compound and'of aldehyde with about onehalf mole of the amine. j The product obtained by the above condensation reaction appears to consist predominantly of N,N-bis (hydroxy aralkyl) diamines, with smaller amounts of both higher and lower condensation products. Investigations by Donia et al. (Journal of Organic Chemistry, vol. 14, pages 946-951 (1949)) have indicated that compounds of this character, containing an ethylene diamine group, react with carbon disulfide in two stages'to form cyclic thioureas, as follows:

i The above reaction with carbon disulfide is carried out by mixing the reactants and then heating at a moderately elevated temperature, suitably in the range of from about F. to about 300 .F., in.the presence or absence of Equimolar proportions of the diamine condensation product and carbon disulfide may be employed in the reaction, but preferably an excess of carbon disulfide is employed, amounting to at least a two-fold excess over the amount theoretically required. Metal derivatives of the reaetion -produets prepared as described above are obtained by replacing the hydroxyl hydrogens of the hydroxyaryl groups with their equivalent of a'metal. Any metal in general may be employed for this purpose which can be suitably reacted to form the oxyaryl derivatiyes, such as for example sodium, potassium, magnesium, calcium, barium, manganese, iron, tin, copper, cobalt, and soforth. Because of the generally superior detergency characteristics of compounds of alkaline earth metals and zinc, the metal is preferably'chosen from this group. With particular advantage,.where the compounds are to be employed as additives where the character of the combustion chamber deposits is an important consideration, the metal is 'chosen'fromthegroup consisting of magnesium and zinc. For regular heavy dutymotor oils, however, the heavier metals such as calcium andbarium may be suitably employed, .As discussed hereinabove, the derivatives may be a normal metal salt, i. e., wherein the metal is conjnected only to oneor more'oxyaryl' groups of the amine condensation product, or it may be a hydroxy-metal or alkoxy-metal derivative, wherein the alkoxy group contains from lto carbon atoms, as disclosed'in the aforementioned application oilKluge et'al. The metal derivative, may be prepared conveniently by :themethod comprising reacting the amine condensation product with a metal methylate or other lower alcoholate of a metal, employing approximately equal molar proportions to obtain the normal metal salt, and employing at least two moles ofmetal alcoholate for each mole of the aminefcondensatio'n product to obtain the alkoxymetal derivative. The hydroxy-metal derivatives may be readily obtained by hydrolysis of. the alkoxy-metal de- .rivatives obtained as described'above. The normalmetal ,salts may also be obtained by various. other well-known reactions, such Lasfby reacting the amine condensation product with metal hydroxide. Conversion to the metal derivatives may ,be carriedgout either before or after the 'ine. condensation product is reacted with carbon disulfidem V V V The novel additives of this invention may be employed in lubricating oils in various amounts, rang'ing from very small'aniounts-up to amounts representing'thelimits of their solub'ilities, depending uponthe effect-desired- .For ordinary purposes, they'are'suitabl'y employed in amounts within the range of from about 0.1 to about 5.0 percent by weight, and preferably within the range of from about 0.25 to'about 2.0 percent by weight of the lubricating composition. In additionto theselc'ompounds, other lubricating oil additives may also be employed if desired such as extreme pressure agents, pour depressants, corrosion inhibitors, and so forth. r r

In order to more fully disclose the invention, the preparation of atypical compound of this novel class of lubricating oil additives is described in detail in the following example.

EXAMPLE 1 .A condensation'prpduct .was. prepared by reactiug an alkyl phenol with formaldehyde and with ethylene diamine. Ihe' alkyl phenol was, a purchased product having a hydroxyl number of 128 'and a molecular weight of 440, indicating that it consisted chiefly of an alkylated phenol containing an average of 25 carbon atoms in the alkyl group. In carrying out the. condensation, 2640 grams (dmoleslof-thealkyl phenol, 262 grams (3 moles) of ethylene 'diam'ine' and 45 liters of ethyl alcohol were introducediinto a fiaskand 525 'grams (.6fmoles 'plus 5 percent excess) of formaldehyde the form "of a' 36 percent "solution were addedfslowly overiaflholir period.

. hours.

The reaction mixture was then heated under reflux for 8 The reaction product was recovered by cooling the reaction mass to room temperature, dissolving in ether and washing the ether solution first with a saturated sodium chloride solution and then with water until neutral to Brilliant Yellow. The ether was then stripped ed, with toluene added as a make-up solvent until the toluene boiling point was reached, and the toluene finally stripped 'ofi under a vacuum. 'The product thus obtained contained 2.51 percent of nitrogen, as compared to the theoretical value of 2.91 percent for the compound v oil were then added, the solution filtered and stripped at 270300 F. for one hour under a vacuum of 5 millimeters of mercury to remove the solvent. 305 grams 7 of product were recovered, which analyzed 3.1 percent lubricating oil additive of the'dete'rgent type in compariof sulfur, as compared with the theoretical value of 2.4 percent (calculated, on the basis of a 75.3 percent concentrate) for the compound 7 OH 1 OH C z-CH2 V CH N N oH,

0 J V l,3-bis-(2-hydroxy-alkyl (C25) henzyl)-2-imidazolidinethione The product therefore appeared to be predominantly the :cyclic thiourea shown above inadmixture with a small amount ,of the dithiocarbamic'acid inner salt first formed in the reaction (Equation I).

The normal magnesium salt'of the above reaction product, was prepared in 'thefollowing manner: 302 grams of the lubricating oil solution,pcontaining approximately 0.29 mole of the reaction product, were mixed with 224 millilitersof' a 0.31 molar methanol solution of magnesium methylate (0.29 mole) and the mixture allowed to react. After the reaction was completed, a ,300 SAE gradelubricating oilwas addedfisufficient to form a 50 percent concentrate of the? reaction product, and the solvent stripped off at 90 C(for 2.5 hours under a vacuum of 5 millimeters of mercury. The solution thus obtained analyzed 5.85' percent ash and 1.16 percent magnesium, as compared with the theoretical values of 5.81 percent and 1.16 percent, respectively, calculated for a 50 percent-solution of the normal magnesium 'salt of!1,3-bis-(2-hydroxy-alkyl(C25)benzyl)-2-' imidazolidinethione. i

The superior-properties of the above compound as a son with the'corresponding compounds@ofjthe priorart are shown in Tables I and II 'below. r v

All of the additives shown' in'the tables were derived from coudensatien; products obtained 'by interreacting alkyl phenols with formaldehyde and withethylene diamine in the manner described in Example '1. The nor- -mal magnesiurn salt was obtained by reaction o'f' su'ch a condensation 'productiwith magnesium. methylate in approximately jequimolar.;proportious,' as. described in Example 1,, The normalHzincE salt wasgobtained by first, forming the sodium salt'by reaction jof the condensation product with fsodiurn' butylate, andtheu reactingithis sodium salt with zinc, chloride The normal barium salt wasobtained by'reacting the onaensafioaerbduferwim I I V I barium hydroxide. The methoxy rdagnesium derivatives were obtained by reacting the condensation product with magnesium methylate, employing two mol proportions of magnesium methylate for each mol proportion of condensation product, as described in the aforementioned ap plication of Kluge et al. The disulfurized magnesium derivative was obtained by reacting the condensation product with sulfur monochloride, employing approximately,

equimolar proportions of the two reactants in pentane solution, and then converting the sulfurized product obtained to the magnesium derivative as described above."

In preparing the mono-sulfurized compounds the disulfurized condensation product, obtained as' described above, was treated with sodium sulfite in sodium hydrox-- ide solution, employing approximately equimolar proportions of the two reactants. The sulfurized compound resulting from this treatment was then converted to the magnesium and to the methoxy-magnesium derivatives as described above. The above compounds were employed in the form of 1 percent solutions in the base oil, which was a refined parafiiinic distillate'lubricating oil of medium viscosity. For convenience, the compounds are referred to in the tables as derivatives of the N,N-bis-(hydroXy-alkyl-benzyl)-l,2-diamino ethanes, which are thought to comprise the chief component of the condensation products.

The oxidation test of Table I is an uncatalyzed oxidation test which is primarily useful in indicating the oxidation directing properties of lubricating oil additives, that is, whether they are pro-oxidants or anti-oxidants. The apparatus employed in this test is a closed system through which oxygen is circulated, comprising an oxidation tube,

, cylinder.

Table H below also shows istiesunder conditions simulating those encountered in crankcase lubrication of a lubricating oil containing the compound of Example 1 in comparison with oils cont'aining the corresponding unsulfurized compound and the sulfurized compounds of the prior art. The Toettcher varnish test and the high temperature deposits test of the table are bench tests which have been found to correlate well with the lacquer forming and the. oil ring sticking characteristics of a cylinder oil in actual service. In the Toettcher varnish test, a weighed glass cylinder is immersed in a sample of the test oil maintained at 350 F. and agitated by a centrifugal mixer. Copper bafliles are also immersed in the test oil to act as oxidation catalysts.

After 13 hours the test is terminated and the glass cylinder removed, washed with gasoline, dried and reweighed.

The amount of varnish deposited on the cylinder is the difference between the initial and final weights of the The neutralization number of the used oil is also determined. The high temperature deposits test is carried out by repeatedly dippingan aluminum cylinder one inch in diameter and three inches long into a beaker containing a sample of the test oil maintained at 525 F. for a period of 20 hours. The test specimen is then washed with pentane and dried, and the weight of deposits found by the increase in weight. The test specimen is then brushed to remove loose deposits and reweighed to determine the amount of varnish-like deposits, A lubrieating oil of the same type as that employed in the oxidation test of Table I was employed in these tests.

Table IIE-Detergency tests a scrubber for removing volatile acids, water and carbon dioxide, and a calibrated burette for measuring the oxygen Tqettcher High e pe a- ,F nish Test, 350 ture Deposits consumption. the oxidation tube is immersed in an oil F. Test 0 bath maintained at 339:? F. In carrying out the test,

Additive 21 grams of the test 011 are placed in the oxidation tube, Weight of air is displaced from the system and oxygen (about 98.3 iy e ght f 1% .N posits, mg. percent purity) is circulated at a constant rate of 2.2 liters 5; 5 per hour for the period of the test, ordinarily for 40 Total Adherent: hours. As the oxygen is consumed, thereby diminishing i e losed s stem valve automaticall n ase il) 15.2 6.0 452 32s: the pressure e y S y 1% of Mg salt of N,N-bis-(hyopen to permit oil from a reservoir to drain into the droxy-alkyl (C22) benz 1 burette to reestablish the pressure, and the amount of diamiflo 125 115 15 1% of Mg salt of sulturizod N,i\ oxygen consumed is read directly from the oil level in the bjs (hyd oxy alkyl (C25) hem zyl)-l,2-d nmiuo ethane 14. 8 8.1 34 14 burette A .leighed glass slide is suspended in the test 1% of Mg Salt of disulmrized 011 during the test, and at the end of the test the slide gm gis n drox -aii i 025) 6 83 enzy 'aminoe ane 12.7 6.5 10 is removed, washed with pentane, dried and reweighed to 1% ofMg SE11? reaction prod? determine the amount of varnish deposition. of N, y-a y (C25) benzyl)-1,2-diammo ethone with carbon disulfide (Ex- Table I.Oxzdatz0n test ample 1) 2.0 3.9 79 29 V Oxygen T As shown by the above tables, the compound of this armsh, absorp- N. l\- Additive mg. tion,mil1i- Used invention had excellent detergency characteristics fully flgiff' 011 equivalent to those of the corresponding unsulfurized metal derivative in a mineral lubricating oil, and was None (base 0) m8 21/40 38 substantially without efi?ect upon the oxygen absorption 1% of Ba salt of N,N'bis(1iydro; yor acidity increase of the 011. On the other hand, all 2&5; 1 8 58/17 150 of the corresponding unsulfurized compounds of the prior 1% oi Ziisizlii: oFiLN'bism drox 60 art tested had a strong pro-oxidant effect, and their sulggi ii' f iifl 42 55/20 m9 furized derivatives of the prior art were entirely, or al- 1% of Mg salt of N,Nb is(h ydr0xymost entirely, lacking in detergent efiect.

Elli?if f fi ii'if f ffgf2; M 54/15 Obviously many modifications and variations of the 1% of Mg Sm ofsuliurized N,N'bisinvention, as hereinbefore set forth, may be made with- 54/38 out departing from the spirit and scope thereof and, i7 r1gr saito ii ti mf amgi'pgtherefore, only such limitations should be imposed as i'ox -a 5 enzy minim f 11.0 26/40 31 are indicated in the appended claims. 1% of inethoxy-Mg derivative of We claim:

(LU 55/13 123 1. lubricatingcomposition comprising a mineral lu- 1% o 'rnetl iia -Mg tigrrlvatlve n bricatmg 011 containing about 0.1 to about 5.0 percent ifg g$fi ggg gfg il 55/29 121 by weight of a metal derivative of the reaction product %I I% a f a g p at an elevated temperature of carbon disulfide with a igg fii, 55;, i s, ii fififi j condensation product of one mol equivalent ot a hy- Sulfide p u 23/40 droxyaromatic compound with about one mol equivalent tlie detergency character 2.fA 'lub rieatin'gcomposition comprising "a mineral 'lu-v bricating oil contai 'iing about 0.1 to about 510 percent by weightfofa metalderi'vative of the reaction product ati'an elevatedie rnperature of 'cjarb'o'n disulfidewith a condensation product of one moi equivalent of a hydroxyaro'rn'atic compound, Containing an alkyl'substituent group or 'sufiieient eh'ain length to impart oil-solubility to thie fin'al product, withabout one 'mol equivalent of an j'aliphati'cj aldehyde and 'at least about one half, mol equivalentef an aliphatic, amine eontaining tWo rimar amine 'gi'oup'sf'sepalfate d bytwocarbon atoms, said metal derivative having thehyd'roxylhydrogens of the said reaction'bioduct replaod by a member of the group consisting or metals, metal hydroxides, and metal alkoxides Containing from 1't'o"5 carbon atoms.

3. 'A lubricating Composition comprising a mineral lubricating oil containing ab out'OJ to about 5 0rpercent by. Weight 'of' 'af'metal derivative of the reaction product af'anel'eyated temperature of carbon "disulfide Withf a cdndensa'tionfproduct "off-one" mol equivalent of an alkyl phenol, in'which 'an alkyl substituent" on the benzene nucleus contains. fromjabout 5 to'about 30 carbon atoms, with about one I'nol"equivalent"of formaldehyde and at least-about one halfmol equivalent of ethylene diamine,

sal'dmetal derivative having the hydroxyl hydrogensjof the'said reactionprotluct replaced'by a member of the group consisting of metals, metal hydroxides, and metal alkoxides containing from 1 to '5 carbon atoms.

4.-Claim '3 wherein the metal is a member of the group consisting of alkaline earth metals and zinc.

5.Clai'm '3 wherein the metal is magnesium. V

'6. Claim 3'Wherein the'metalis Zinc.

References Cited in the file of" this patent UNITED STATES PATENTS Oberri ght July 11,1944 'Vaughnet al.- May 13, 1952 

1. A LUBRICATING COMPOSITION COMPRISING A MINERAL LUBRICATING OIL CONTAINING ABOUT 0.1 TO ABOUT 5.0 PERCENT BY WEIGHT OF A METAL DERIVATIVE OF THE REACTION PRODUCT AT AN ELEVATED TEMPERATURE OF CARBON DISULFIDE WITH A CONDENSATION PRODUCT OF ONE MOL EQUIVALENT OF A HYDROXYAROMATIC COMPOUND WITH ABOUT ONE MOL EQUIVALENT OF AN ALDEHYDE AND AT LEAST ABOUT ONE HALF MOL EQUIVALENT TO AN AMINE COMPOUND CONTAINING TWO PRIMARY AMINE GROUPS SEPARATED BY TWO CARBON ATOMS, SAID METAL DERIVATIVE HAVING THE HYDROXYL HYDROGENS OF THE SAID REACTION PRODUCT REPLACED BY A MEMBER OF THE GROUP CONSISTING OF METALS, METAL HYDROXIDES, AND METAL ALKOXIDES CONTAINING FROM 1 TO 5 CARBON ATOMS. 